1. Field of the Invention
The invention relates to apparatus and accompanying methods for, illustratively, preventing telephone toll fraud and which rely on the use of centralized voice verification to authenticate a party claiming a particular identity and requesting service, i.e. access to a telephone network, from a service provider, e.g. a local or long distance telephone company.
2. Description of the Prior Art
Over the past few years, telephone toll fraud has become a significant and growing problem to telephone service providers (both local and long distance carriers), telephone equipment owners and manufacturers, and both individual and business telephone service subscribers. Currently, annual losses to business and individual subscribers arising from this fraud are estimated to reach approximately $3 Billion.
In general, toll fraud involves the theft of network access by an unauthorized caller. This fraud occurs when a caller gains unauthorized access to dial tone associated with service charged to a legitimate subscriber. As a result, once that caller receives dial tone, that caller subsequently places one and frequently many telephone calls, typically anywhere throughout the telephone network, with the ensuing telephone charges ultimately being billed to the subscriber. Given the monthly billing mechanisms used with nearly all telephone carriers, these charges are billed generally several weeks after the fraudulent calls are made, thereby frustrating attempts at preventing the fraud from occurring in the first instance.
Calling card fraud is a particularly pernicious and widespread variety of toll fraud which, owing to the magnitude of the theft of service involved, has become essential to eliminate.
Currently, to place a calling card call, a caller need only dial a destination number preceded by "0+", and then following a "bong" tone, enter a calling card number, which itself includes an account number to which the call is to be billed followed by a personal identification number ("PIN"). The account number, for a local Bell operating company ("BOC"), is generally a ten-digit telephone number of the subscriber, complete with area code. In this instance, the PIN is a four-digit number assigned by the BOC to that subscriber. Immediately after the calling card number including the PIN is entered, that number is validated. In doing so, a local equal access switch which is then servicing that caller launches a query message through a common channel signaling network to a service control point ("SCP") appropriate to the entered calling card number. A database of calling card numbers is then accessed to determine whether the entered number is designated to be valid or not. Each carrier, whether a long distance or local carrier, typically maintains one or more service control points with corresponding internal databases of calling card numbers issued by that carrier along with the status of each such number. If the calling card number is valid, the SCP sends a response message back through the signaling network to the local switch. The switch, in turn, simply routes the call dialed by the subscriber onward through the network to the destination number.
In calling card fraud, a caller, totally unbeknownst to a subscriber, obtains a calling card number of that subscriber and then simply places a calling card call charged to that calling card number. The subscriber does not realize the fraud has occurred until he or she receives a subsequent bill for service. One way a caller obtains the number is to simply watch public telephones as subscribers punch in their numbers and then note each entered calling card number as it is entered. Alternatively, a caller may station himself close to a subscriber and simply eavesdrop of a conversation, during which that subscriber provides his or her calling card number to a telephone operator, and record the spoken number. Fraudulent callers may also use a variety of scams to call unsuspecting subscribers and, through a ruse, deceive them into revealing their calling card numbers. Now, regardless of the particular technique used to gain a calling card number, once a caller enters a valid calling card number, that caller is then granted access to call anywhere throughout the entire worldwide telephone network. Consequently, as presently constituted, the telephone network simply completes the call, with concomitant charges billed therefor, before its fraudulent nature is discovered. Although individuals are liable for a relatively small amount of illicit calling card telephone charges, typically $50, no such limit exists for business and other users. Nevertheless, given the sheer and growing magnitude of the losses currently flowing from toll and particularly calling card fraud, telephone carriers are increasingly turning their attention to develop ways to limit and preferably eliminate this (as well as other) fraud from occurring.
One such technique aimed at reducing calling card fraud involves real-time analysis of calling patterns to detect abnormally high usage numbers and blockage of further calls billed to any such number. In that regard, once a calling card number is fraudulently obtained, that number is often quickly disseminated to quite a few callers and, to allude detection, heavily used by all of them over a relatively short interval of time, such as a few days, before a new number is fraudulently obtained, disseminated, used and so on. Thus, calling card fraud often manifests itself as a concentrated burst of grossly excessive usage above a normal calling pattern. Thus, with this technique, a fixed, or statistically varying, threshold might be established for each subscriber based upon his or her recent actual calling pattern. As each calling card call is made to a calling card number, then, during calling card validation, the current frequency of calls billed to this number is measured and compared to a corresponding threshold by an SCP. Once the threshold is met or exceeded, the SCP denies access to all subsequent calls billed to that number until the calling frequency decreases below the threshold. While, at first blush, this technique may seem to afford adequate protection, it suffers from a number of drawbacks which severely limit its attractiveness. First, while this technique can reduce the total number of fraudulent calls billed to a given calling card number, this technique will not completely eliminate these calls and the cost associated therewith. In fact, in order for this technique to detect fraud, a relatively large number of fraudulent calls must occur in order to appreciably raise the calling frequency to the threshold. The cost of these calls must still be absorbed either by the subscriber and/or the carrier(s) involved. Second, this technique does not discriminate among callers. Once the threshold is met or exceeded for a calling card number, network access is denied to anyone subsequently entering that number. Hence, the true owner of that number would be denied access just as would any fraudulent caller. Inasmuch as calling card fraud occurs without knowledge of the true owner, once the fraud is detected, the true owner is denied service and, as a result, greatly inconvenienced.
In an effort to mitigate service denials and the ensuing inconvenience to valid subscribers, other techniques that ostensibly discriminate amongst individual callers have proposed to counter calling call fraud. These techniques rely on independently and uniquely verifying the identity claimed by the caller apart from verifying the calling card number. The intent in doing so is to allow a call from a true owner of a calling card number, i.e. a valid subscriber, to be routed while blocking calls from others that have fraudulently gained access to that number. With respect to the general field of access control, various approaches have been proposed which rely on identifying individuals through highly unique biometric characteristics, such as eye retinal patterns, fingerprints and human voice characteristics. Given the nature of the telephone network, the only practical biometric characteristic is voice. Fortunately and statistically speaking, a single human voice is highly unique amongst a very large universe of individuals.
In this regard, U.S. Pat. No. 5,125,022 (issued on Jun. 23, 1992 to A. K. Hunt et al--the '022 patent) describes a technique for authenticating a caller through voice verification, and specifically for authenticating callers who are placing verbal orders through a telephonic order entry service or a telephonically accessed financial service. Here, voice verification circuitry is completely resident at a line end of the network and specifically within equipment at a service provider site. This technique relies on comparing a password just spoken by a party claiming to be a specific caller against the same password previously spoken by that caller and stored for subsequent use. If a match occurs, at least to within a sufficient accuracy, then the party is verified to be the caller and is granted access to the desired service. Inasmuch as this technique is simply line-to-line based, the telephone network itself is totally transparent to the use of voice verification. However, to efficiently prevent calling card fraud, voice verification would need to be embedded within the telephone network itself, i.e. on the trunk rather than the line side of the network, and particularly in a cost-effective manner that is readily compatible with existing telephone switching equipment as well as engender only minimal, if any, inconvenience to callers. The '022 patent simply fails to teach how voice verification could be accomplished in this manner within the telephone network itself.
In view of the deficiencies in the '022 patent, one voice based caller identification technique, that might be used within the telephone network itself, relies on incorporating a voice template of a caller into a magnetic strip affixed to the rear of a calling card. During the course of "swiping" the card past a suitable reader in a telephone, the telephone would read the voice template of the caller. Thereafter, suitable speech synthesis and recognition/verification equipment situated within the network would ask the caller to speak the word(s) or number(s) recorded in the template, and finally confirm or reject the caller, and hence signal the local switch to grant or deny network access, based upon whether the spoken speech matches, within a suitable accuracy, that previously stored in the template. Unfortunately, if the calling card is lost or stolen, then its true owner is forced to re-enroll and store a new voice template on a replacement card. This imposes an added burden, which is quite inconvenient, on the owner. Furthermore, since enrollment is not supervised, a party who illicitly gains possession the card could, if properly equipped, simply record his or her own voice template on the card and thereby fraudulently gain network access until the fraud was discovered some time later. Alternatively, a subscriber could be issued a so-called "Smart card" which incorporated an internal microcomputer to store voice data, and particularly in encrypted form, and/or perform all or a portion of the voice analysis. Unfortunately, this technique is extremely impractical as it would only function with those telephones that can interface to these particular cards. Hence these techniques will not function, at all, with the vast base of telephones already in service, none of which possess the requisite capabilities.
Thusfar, in spite of the tremendous cost savings that would flow from implementing a caller verification technique that effectively eliminates toll fraud in the telephone network and the uniqueness inherent in the human voice and hence the appeal of using a voice based verification technique, the art has failed to teach a practical implementation of this technique for use in the telephone network.
Consequently, a need still exists in the art for a technique, specifically apparatus and accompanying methods, for incorporation into a telephone network that, through voice verification, can independently verify an identity of a caller. To be practical while still providing sufficient security and caller convenience but with minimal inconvenience to callers, this technique should not rely on storing voice data on a calling card and, importantly, should be compatible with all telephones currently in service. Furthermore, this technique should be cost-effective and readily compatible with existing switching equipment currently used within the telephone network itself.